The American Cancer Society (ACS) has recently made notable revisions to their breast cancer screening guidelines, but the evidence supporting indisputable guidance for women still remains incomplete, suggest Nancy L. Keating, MD, MPH, Department of Health Care Policy, Harvard Medical School, Boston, and Lydia E. Pace, MD, MPH, Division of Women’s Health, Brigham and Women’s Hospital, Boston, in their discussion of the implications of the new guidelines in their accompanying editorial (Keating NL, Pace LE. JAMA. 2015;314:1569-1571).
The updated recommendations are the first revisions to the ACS breast cancer screening guidelines since 2003. The new guidelines, which address screening for women at average risk for breast cancer, outline changes to current protocol related to the starting age and frequency of mammography, and utilization of routine clinical breast examination (CBE). The ACS now recommends annual mammography for women aged 45 to 54 years, and then biennial mammography at age ≥55 years. Women with only ≤10 years life expectancy should refrain from breast cancer screening.
The new guidelines also recommend against routine CBE for women of any age, a recommendation based on low-quality evidence, according to Drs Keating and Pace, who note that currently “there are no trials comparing the effects of CBE vs no CBE on breast cancer mortality.”
Drs Keating and Pace cite many contradictory studies about the frequency of mammography and their benefits versus harms. Because there is limited decisive evidence about screening mammography, they note that there is no true answer to whether a mammography for a woman at average risk aged >40 years is necessary.
“Especially for average-risk women, decisions to undergo regular mammography screening must also consider the harms of mammography—most notably the possibility of overdiagnosis and resultant overtreatment…and also the risks of false positives and unnecessary biopsies,” Drs Keating and Pace state.
They are quick to add that whether cancer is found by mammography or not, the evidence suggests that screening mammography for women in their 40s and 50s only decreases breast cancer mortality by 15%. With the risk for breast cancer being low for women in this age-group, the benefit of 15% translates to a very small absolute benefit. The only way to truly raise the absolute benefit of mammography, they say, is to identify and screen women at higher risk for breast cancer.
Drs Keating and Pace certainly understand the reasoning for the new screening guidelines, and admit that the message of the ACS is now more consistent with the guidelines outlined by the US Preventive Services Task Force. However, they believe that the future of breast cancer screening lies in understanding risk.
“If women who are at higher risk of aggressive breast cancer could be more accurately identified,” they note, “it would be possible to more definitively identify those women who are most likely to benefit from earlier and more frequent breast cancer screening and less likely to experience the related harms,” they conclude.